Transcription: The process of welding two separate pieces of metal together dates back to the fourth millennium BC. But until the end of the 19th century, iron and steel could only be joined together in a forge. With the invention of the carbon arc in 1807 and the coated electrode in the early 1900s, the arc welder became possible. But was not used widely until the late 1920s. Today, arc welders are used commonly in many manufacturing industries.
(.mp3)